1. Field of the Invention
This invention relates to a fuel feed system for carburetors on motorcycles, which comprises a main fuel tank for storing alcohol therein, a main fuel passage for communicating the main fuel tank with a carburetor, a switch cock provided at an intermediate portion of the main fuel passage, an auxiliary fuel tank for storing gasoline therein, an auxiliary fuel passage for communicating the auxiliary fuel tank with the carburetor, and a measuring pump provided at an intermediate portion of the auxiliary fuel passage, whereby the fuels stored in the main and auxiliary fuel tanks are fed to the carburetor by operating the switch cock and the measuring pump, respectively.
2. Description of the Prior Art
In a fuel feed system for carburetors on motorcycles, a main fuel tank is provided at a front side of an upper portion of a main frame of a motorcycle, and an auxiliary fuel tank at a rear side of the upper portion of the main frame. The main fuel tank is communicated with a carburetor via a main fuel passage provided with a switch cock at an intermediate portion thereof. The auxiliary fuel tank is communicated with the carburetor via an auxiliary fuel passage provided with a measuring pump at an intermediate portion thereof. A main fuel such as alcohol is normally supplied from the main fuel tank to the carburetor so as to operate the engine. When it is necessary to improve the engine-starting conditions, for example, at a low temperature, the measuring pump may be operated to supply an auxiliary fuel such as gasoline from the auxiliary fuel tank to the carburetor. In order to allow a rider on the motorcycle to operate the switch cock and measuring pump as he sits on a seat thereof, it is desirable that the switch cock and measuring pump be disposed within the area that the rider can reach them in his seated position and in such a manner that the switch cock and measuring pump may not be obstacles to action of the rider.
The measuring pump is preferably a diaphragm type pump. A diaphragm and an actuator rod in a conventional diaphragm type pump are joined together by sandwiching the diaphragm at its central movable portion between a pair of holding plates, and caulking the actuator rod to these holding plates. In this structure, the diaphragm and actuator rod cannot be separated from each other. Accordingly, when it is necessary to repair either the diaphragm or the actuator rod by replacing it with a new one, it is also required to renew the other as well, which is still in a normal condition. It is uneconomical to use such a measuring pump. Furthermore, when the actuator rod is caulked to the holding plates, the gilt on the caulked portions thereof may come off in some cases. This results in the formation of rust on the mentioned portions of the actuator rod and holding plates, and the rust would be mixed in a treating liquid.